2. Methods

Methods (Location)

The location that we are surveying is the river at Sungei Ulu Pandan and the canal behind it, passing by the Dover train station. On the banks of the river, there is an abundance of grass. Egrets frequent the area, flying low above the water surface and resting on the banks. The banks are blocked by low railings, making collecting sample water from the shores an unfeasible idea. A few bridges span across the river, and these spots allow an efficient and safe way to collect sample water. Located across the river is the Aquatic Science Centre, a research laboratory specialising in studying water quality (Singapore Delft Water Alliance , 2012). The canal generally has rather little water, most of it concentrated in the middle. Hence, collecting water from a bridge over the canal is a feasible and safe idea. Among the stretch of the canal, there are multiple rest areas, ideal for the testing of the water. However, at the Sungei Ulu Pandan river, there are seemingly construction projects going on (Dai Lin, 2011). This may pose a difference to the results collected, as among the 3 chosen collection sites, only this particular one has such interference.

Methods (Testing Equipment)

Testing the sample water would require specialised equipment. The table below categorises the different equipment needed for the 9 water parameters:

Equipment

Function

Temperature Sensor

It measures temperature simply by submerging it in liquids, solutions, acids and bases.

Colourimeter

With 4 pre-programmed wavelengths, the colourimeter measures the amount of light transmitted to determine the concentration of a solution. Used for phosphates testing.

Dissolved Oxygen Probe

The probe determines the amount of dissolved oxygen in aqueous or liquid solutions. Dissolvedoxygen and biochemicaloxygendemand testings require such probes.

Nitrate Ion-Selective Electrode (ISE)

Only applicable in aqueous or liquid samples, this instrument allows the measurement of the concentration of the nitrate ion.

pH Sensor

Used in measuring the pH values of liquid samples, they contribute greatly when testing the water quality. The usage is similar to a typical pH meter, enhancing its ease of use.

Turbidity Sensor

It aids in measuring turbidity, or the measurement of cloudiness in liquids. The higher the amount of particles in the water, the higher the turbidity. It uses infrared light and a photodiode to measure the amount of particles scattered, resulting in the measurement of turbidity.

The above equipment are from Vernier Software and Technology, LLC.

Equipment

Parameter

Temperature Sensor

Temperature

Colourimeter

Phosphates

Dissolved Oxygen Probe

Dissolved oxygen, Biochemical Oxygen Demand (BOD)

Nitrate Ion-Selective-Electrode (ISE)

Nitrates

pH Sensor

pH Value

Turbidity Sensor

Turbidity

Total solids and fecal coliform testings do not require such equipment from Vernier

We have chosen 3 sampling sites (among 6 others), each of them having a bridge or an elevated platform to stand on. Of these sampling sites, 2 of them are part of canals and the other being the start of the Sungei Ulu Pandan river. Due to the risk of entering the canal, railings have been placed on both banks, restricting access. The next best alternative is collection from a bridge or an elevated platform. They ensure that the water collected is away from the shore and has minimal risks. To ensure maximum safety, apparatus consisting of a rope and a bucket are utilised. Both ends of the rope are tied tightly to the bucket’s handles and the other end being tied to a stable object (for example, a railing). The bucket would be then lowered down into the canal or river for the collection of sample water. After hauling up the bucket, the water is transferred into 1.5 litre bottles. There would be 2 bottles per site.

There are a few water parameters to be taken note of. They would be Dissolved Oxygen, Nitrates, Temperature, Biochemical Oxygen Demand and Fecal Coliform. For Dissolved Oxygen, Temperature and Nitrates, their readings have to be taken onsite, not brought back to the laboratory for later testing. The amount of such parameters would be affected even within a short period of time, such as temperature change due to different locations. Bacteria in the sample water may consume oxygen and nitrates, changing their amount gradually, hence it is important for readings to be taken immediately. Sterile bottles should be used when collecting water for Biochemical Oxygen Demand and Fecal Coliform testings. This is to minimise any contamination which would lead to an increase in bacteria numbers. The readings for two of such parameters would be significantly affected.

Minor actions such as labelling of the bottles should be taken seriously, in order to decrease any chances of mix up. Upon arrival back at the laboratory, the bottles should be placed into a refrigerator so as to have the parameters remain at a constant. For Biochemical Oxygen Demand, the sterile bottles containing the sample water should be placed in a shaded area, with a temperature of 20°C. For convenience, a trolley would be used to place the bottles and equipment.

After we have found all the readings for the 9 water parameters, we would use the designated ‘Q’ values charts. These charts are specific for each parameter, utilising the final readings and the ‘Q’ values. Once we determine the ‘Q’ values for all water parameters, we would use a tabulated table to find out the total. Different parameters have different weightings. We would then be able to find the overall Water Quality Index.Maps of the 3 collection sites